1. Field of the Invention
The present invention relates to high-resolution comparators and, in particular, to a comparator that improves sensitivity by reducing the effect of power supply, ground and randomly occurring noise.
2. Description of the Related Art
An analog-to-digital (A/D) converter is a device that converts the instantaneous value of a voltage signal into an equivalent digital representation. Typically, the A/D converter utilizes a comparator to compare the instantaneous value to a series of reference voltages to determine which of the reference voltages is greater than the instantaneous value.
Recently, with the movement towards increased computing ability and reduced power, there is a need for 16-bit A/D convertors which can operate on 4.5 volts, using a 4 volt reference. One problem with resolving 16-bits in a 4 volt full scale A/D converter, however, has been that with 16-bits, each bit transition is equivalent to only 60 uV. Therefore, to achieve a 1/2 least significant bit (LSB) accuracy, a sensitivity of 30 uV must be achieved.
Sensing these minute voltages not only requires a very sensitive comparator, but also requires a comparator with extremely high noise immunity to both the power supply and ground as well as from randomly occurring sources of noise. Thus, there is a need for a high-resolution comparator that has extremely high noise immunity.